1. Field of the Invention
The present invention relates to a composite material comprising a resin reinforced with carbon nanotubes.
2. Description of the Related Art
A carbon nanotube is a single tubular molecule where a large number of carbon atoms are continuously bonded in such a state that six-membered rings are formed by sp2 bonding and possesses a structure of nanometer order. The end part of the carbon nanotube is closed with forming a hemispherical structure by incorporating five-membered rings in part. Moreover, the above carbon nanotubes form single-layered tubes, or tubes of various sizes can sometimes be layered in a nested form to form multi-layered tubes.
The above carbon nanotubes are expected to have application to various uses such as one-dimensional wires, catalysts, cold-cathode elements, and hydrogen storage substances owing to mechanical and structural properties derived from its specific structure. In addition, composite materials reinforced with the carbon nanotubes possess excellent functional properties such as electric conductivity.
As the above composite material, a resin composition containing 0.1 to 50 parts by weight of a carbon nanotubes and 99.9 to 50 parts by weight of a synthetic resin is known, for example (Japanese Patent No. 2862578).
The above resin composition contains carbon nanotubes having a diameter of 3.5 to 70 nm and an aspect ratio of 5 or more and a thermoplastic or thermosetting resin in respective amounts of the above ranges and is produced by mixing an aggregate of the carbon nanotubes with the thermoplastic or thermosetting resin.
However, in the above resin composition, it is difficult to homogeneously disperse the carbon nanotubes in the resin because the tube is in an aggregate form. Moreover, the carbon nanotubes have a low chemical activity owing to a structure where a large number of carbon atoms are continuously bonded, and hence is poor in wetting ability toward water and various organic solvents. As a result, the resin composition is week in bonding force between the surface of the carbon nanotubes and the resin and hence has an inconvenience of low mechanical strength such as tensile modulus.